2 Answers
2

That sure looks like sensor dust, for which I'd recommend seeing the answers in the Best way to clean a DSLR sensor thread. The spot may appear "randomly" because it only appears when you're using a narrow aperture.

That said, it seems you don't have a dSLR, thus no interchangeable lenses which are what usually causes the situation where dust can get inside the camera body. I suppose it's possible that dust got inside the camera through some other way although I think that's a fairly rare occurrence.

If the camera is still under warranty, it's worth a call to the manufacturer.

FWIW, dust (or something) got into my Fujifilm F31fd. That's such a nice little camera that I don't regret sending it in and having it cleaned, even though they charged me a basically-outrageous $100.
– mattdmApr 24 '11 at 3:58

1

That's what I feared, oh well. Seeing as I do more painting than photography at the moment, I'll send it in for repairs if it's still under the 2yr plan. Thanks for the help guys!!! I really appreciate it.
– AlanApr 24 '11 at 4:15

As ahockley said, probably dust. I got one of these blotches on my smartphone camera, and cleaning the lens didn't help, suggesting it was sitting on the sensor, which is obviously a bit difficult to access on a phone. Somebody suggested tapping the phone to see if it moves, and that, remarkably, fixed my problem. Shaking the phone in my hand or even bumping it on my palm didn't do anything, but removing it from it's case and then lightly tapping on a hard surface nudged the dust around, and after a few more taps, off the sensor entirely!